1. Field of the Invention
The present invention relates to foaming cleaning compositions, and in particular to an in situ foaming cleaning composition incorporating a bleach and which is formulated to have utility as a drain cleaner, or as a hard surface cleaner.
2. Description of Related Art
Published Japanese applications to Ishimatsu et al JP 59-24798 and JP 60-32497; JP59-164399,to Miyano et al; and Sakuma, JP57-74379 all disclose, describe and claim a binary foaming cleaner having utility as a drain opener. Miyano et al specifically describes the advantages of a foam in drain opening. Ishimatsu et al and Miyano et al both describe an aqueous peroxide solution containing 0.25-25% active, paired with an aqueous solution of 0.25-6% hypochlorite, and both references teach the inclusion of surfactants with either or both solutions to enhance foaming. None of these references, however, teach, suggest or disclose a thickened formulation, nor any of the advantages and foam characteristics associated therewith.
A hypochlorite composition paired with a chelating agent/builder solution in a dual chamber container is disclosed in U.S. Pat. No. 5,767,055 to Choy et al.
Drain cleaners of the art have been formulated with a variety of actives in an effort to remove the variety of materials which can cause clogging or restriction of drains. Such actives may include acids, bases, enzymes, solvents, reducing agents, oxidants and thioorganic compounds. Tobiason, U.S. Pat. No. 5,264,146, Steer, et al, U.S. Pat. No. 5,630,833 and Taylor, Jr. et al., U.S. Pat. No. 4,664,836 all disclose dry compounds which generate foam when mixed with water in a drain. Kuenn, U.S. Pat. No. 4,691,710 describes a dry in-sink garbage disposal cleaning composition which uses adipic acid and sodium bicarbonate to generate gas upon contact with water. This composition requires mechanical shearing from the disposal to assist in foam generation. Davis, U.S. Pat. No. 4,206,068 describes an exothermic drain opening composition comprising an oxidant and a reducing agent in a compartmentalized container.
In view of the prior art, there remains a need for a foam generating cleaning composition capable of delivering a high percentage of active and possessing a long contact time on non-horizontal surfaces. There further remains a need for an in-situ foam-generating composition which is stable during storage and can be economically formulated.
It is another object of the present invention to provide a composition capable of forming an active-carrying foam in situ.
It is another object of the present invention to provide a composition capable of generating a stable foaming active cleaner.
It is another object of the present invention to provide a dual component composition and containment means which isolates each component during storage.
It is another object to provide a drain opening composition which is formulated to be safe to store and use.
It is another object of the present invention to provide a foaming cleaning composition having utility as a drain cleaner by virtue of its rheology.
It is yet another object of the present invention to provide a drain cleaning composition which is highly effective.
It is yet another object of the present invention to provide a composition having beneficial flow properties during dispensing.
More specifically, the composition is a product of two liquids which are separately maintained prior to forming an admixture during delivery to a surface to be treated, whereupon the admixture generates a foam sufficient for cleaning efficacy and stability. A first liquid includes an oxidant, preferably a hypohalite or a hypohalite generating agent (hereinafter xe2x80x9cthypohalitexe2x80x9d) and a second liquid includes a gas generating agent, preferably a peroxygen containing or releasing agent. As the two liquids are initially separated, the oxidant can be maintained in an environment free of gas generating agent and otherwise conducive to their cleaning activity and stability up to the time of use. When the two liquids are allowed to mix, for example, by simultaneously pouring into a drain, the hypohalite and peroxygen react to liberate oxygen gas in accordance with the following reaction equation:
NaOCl+H2O2xe2x86x92O2(g)+NaCl+H2O 
The liberated gas contacts surfactant in the solution, creating foam which expands to completely fill the drain pipe. The expanded foam contains an excess of the hypohalite, which acts to clean the drain. The resulting foam is stable, and preferably characterized by a density of greater than about 0.1 g/ml, a half life of greater than about thirty minutes; and an initial foam development rate of at least 150 ml/sec for the first 2-4 sec. Foam stability is defined as the foam""s resistance to a force tending to collapse or displace the foam. The foam is further characterized by a ratio of foam:liquid of at least 1:1, preferably 2:1, more preferably 3:1; and a foam height sufficient to yield a greater than twelve cm. column in the drain (as measured from the center, or lowest point of the P-trap, and for a 3.2 cm. diameter drain), more preferably greater than seventeen cm. and most preferably seventeen to thirty-one cm. Most preferred in terms of foam volume and height in the drain, is an amount sufficient to reach the drain""s stopper mechanism, a site of frequent hair and/or soap contamination. Such stopper mechanisms are typically positioned about twenty cm. up the vertical pipe. The foam would preferably contain greater than 0.1% active, more preferably greater than 0.5% active, and most preferably between about 0.75 and 3% active. An active contact time, or foam half life, should be between one-half and two hours, preferably between one and two hours. Foam half-life is the time elapsed between maximum foam volume development and a 50% volume reduction thereof, absent any external forces (other than gravity) acting upon the foam. Further, the foam is self-generating, produced by reaction of composition components, and requires no mechanical agitation or other forms of physical activation.
In a one embodiment of the present invention, the first liquid (oxidant) includes a thickening agent or system, present in an amount such that when the first and second liquids form an admixture during delivery to a surface, the admixture results in a dense, stable foam sufficient for cleaning efficacy and stability. Thus, when the initially separated liquids are allowed to interact, the resulting liquid cleaning composition being delivered to the surface will have the cleaning or bleaching activity and stability appropriate for the cleaning or bleaching of that surface. The term xe2x80x9cliquidxe2x80x9d as used herein may include homogeneous liquids, solutions and suspensions. Preferably an aqueous liquid is contemplated; however, nonaqueous liquids are within the scope of the invention. The thickening agent or system should impart both a viscous component and an elastic component to the corresponding liquid. Most preferably the thickening agent or system imparts a viscoelastic rheology to the corresponding liquid; however, the composition of the thickening system is less important than the attainment of the desired foam qualities as defined herein.
The present invention also relates to a container which maintains the two liquids separately until delivery and provides for such delivery, during which the pH-maintained admixture is formed and delivered to a surface to be treated. The container includes one compartment for the hypohalite containing liquid and another compartment for the peroxygen-containing liquid. Either or both of these two compartments may contain the thickening system or agent which, is present in an amount sufficient to thicken and for stability of the liquid, as described above. According to one aspect of the invention, the container may have separate delivery channels for the two liquid components for delivering the two liquids, whereupon the admixture is formed. These delivery channels may be constructed to provide for the contemporaneous delivery of the two liquids to the exterior of the container, whereupon the two liquids meet to form the admixture. Alternately, the separate delivery channels may communicate with an admixing space in which the two liquids form the admixture and from which the admixture is delivered to the exterior of the container. One example of such a container is that disclosed in U.S. Pat. No. 5,767,055 Choy et al., the disclosure of which is incorporated fully herein by reference.
The present invention further includes a method of cleaning drains which comprises the step of:
pouring into a drain at least one liquid which generates foam in situ, the foam characterized by a volume of at least two times the liquid volume; a density of at least about 0.1 g/ml, a half-life of greater than about thirty minutes, and wherein the foam contains a cleaning-effective amount of a drain cleaning active. It is also within the scope of the present invention to provide a single solution capable of generating the foam upon release from its container, as by pouring into the drain.
Briefly, a first embodiment of the present invention comprises a stable cleaning composition comprising, in aqueous solution:
(a) a first liquid containing an oxidizing agent; and
(b) a second liquid containing a gas generating agent; and wherein the oxidizing agent and gas generating agent react to generate a foam characterized by a density of at least about 0.1 g/ml, a volume of at least two times the liquid volume, a half-life of greater than about thirty minutes, and wherein the foam contains a cleaning-effective amount of a drain cleaning active.
It should be noted that as used herein the term xe2x80x9ccleaningxe2x80x9d refers generally to a chemical, physical or enzymatic treatment resulting in the reduction or removal of unwanted material, and xe2x80x9ccleaning compositionxe2x80x9d specifically includes drain openers, hard surface cleaners and bleaching compositions. The cleaning composition may consist of a variety of chemically, physically or enzymatically reactive active ingredients, including solvents, acids, bases, oxidants, reducing agents, enzymes, detergents and thioorganic compounds. Unless otherwise specified, all ingredient percentages are weight percentages.
For purposes of the discussion of the invention disclosed herein, a typical household sink drain comprises four sections: a vertical section, thence to a U-bend (or P-trap), thence to a 90-degree elbow, and finally a horizontal sewer arm.
A viscous rheology, preferably one with an elastic component, most preferably a viscoelastic rheology, is imparted to the oxidant liquid, preferably by a binary system including a betaine or sulfobetaine having a C14-18 alkyl group, or a C10-18 alkylamino or alkylamido group, and an anionic organic counterion that is thought to promote elongated micelles. Such systems are more fully described in U.S. Pat. Nos. 4,900,467 and 5,389,157 to Smith, and assigned to the assignee of the invention herein, the disclosures of which are incorporated herein by reference. Preferably the betaine is a C14-18 alkyl betaine and the counterion is a C2-6 alkyl carboxylate,
aryl carboxylate, C2-10 alkyl sulfonate, aryl sulfonate, sulfated aryl or C2-10 alkyl alcohols, and mixtures thereof. Most preferably the counterion is an aryl sulfonate, e.g. sodium xylene sulfonate. The counterion may include substituents which are chemically stable with the active cleaning compound. Preferably, the substituents are alkyl or alkoxy groups of 1-4 carbons, halogens and nitro groups, all of which are stable with most actives, including hypochlorite. The viscosity of the formulations of the present invention can range from slightly greater than that of water, to several thousand centipoise (cP). A preferred viscosity range for the first (oxidant-containing) liquid is about 150 to 2000 cP, more preferred is 500 to 2000 cP most preferred is 700-1500 cP. A preferred viscosity for the second (gas generating) liquid is about 0-50 cP, more preferred is 0-20 cP.
A second embodiment of the present invention is a composition and method for cleaning drains, the composition comprising separately maintained aqueous solutions of:
(a) a first liquid including a hypohalite compound and having a viscosity of 150-2000 cP, a static shear modulus of 0.5-5 Pa, a relaxation time of 3-30 sec and a relative elasticity of 3-50 sec/Pa; and;
(b) a second liquid comprising a peroxygen compound.
The liquids (a) and (b) are maintained separately during storage, and combined concurrently with, or immediately prior to use. Preferably, the liquids (a) and (b) are maintained in a dual chamber or compartment bottle, and poured simultaneously into the drain wherein the foam generation occurs. The resulting foam is stable and dense, and contains a high percentage of cleaning active, especially hypohalite, which coats the vertical and upper P-trap portions of a drain. The rheology of each composition provides a favorable rate of foam generation and residence time, resulting in excellent cleaning efficacy. The rate of foam generation should be initially (at initiation of the reaction to about 4-6 sec thereafter) about 150-800 ml/sec, and should be about 3-40 ml/sec after about 15-30 sec. The foam should remain stable for an extended period of time, i.e. at least thirty minutes. The rheology also facilitates filling of the container, e.g., during manufacturing, and affords consumer-acceptable, smooth pouring properties during dispensing and use. The preferred viscoelastic rheology may be imparted by a thickener, preferably a surfactant thickener.
It is therefore an advantage of the present invention that the composition is chemically and phase-stable, and retains such stability at both high and low temperatures.
It is another advantage of the present invention that, when formulated as a drain cleaner the foaming composition provides a long contact time, improving the efficacy of the cleaner.
It is another advantage of the present invention that the improved efficacy resulting from the increased contact time allows for safer drain cleaning formulations.
It is yet another advantage of the present invention that the composition generates a stable, active-containing foam in-situ.
It is a further advantage of the composition of the present invention that the rheology of the composition facilitates container filling, and dispensing.
These and other objects and advantages of the present invention will no doubt become apparent to those skilled in the art after reading the following Detailed Description of the Preferred Embodiments.